This invention relates to container-filling machines, and particularly those utilizing a continuously reciprocating piston wherein a volume of material is filled into a container on each stroke of the piston, the volume being determined by the length of the stroke of the piston.
In setting up for filling operations, the machine will be turned off so that the drive mechanism for the piston will be at rest. The length of the piston stroke is adjusted, relative to the size of the container to be filled. Assuming the initial adjustment is correct, the machine is then turned on so that the piston is continuously reciprocated and a constant volume of material is discharged into the containers for each cycle of reciprocation of the piston. The drive mechanism for the piston is also connected with the conveyor mechanism so that the bringing of the containers to and taking them from the filling machine is synchronized with the piston operation.
It often occurs that the initial adjustment of the piston stroke, made while the machine is at rest, does not produce the desired volume when the machine is in operation. The stroke-adjustment mechanism moves with the piston and thus it is necessary to stop the machine so that the piston stroke can be readjusted. The machine is then put into operation again to see if the new adjustment is correct. If not, the process is repeated until it is. This initial adjustment procedure is undesirably cumbersome and time-consuming.
It also occurs that a particular batch of material being handled will vary in density during a filling run. For example, the material may be in a hopper or reservoir so that some settling will occur. As a consequence, the material may become progressively less dense as the hopper is depleted. With a constant volume being filled into each container, the weight per container will decrease as the run continues. If the weight per container decreases below the normal range of tolerance the machine must again be stopped and the piston stroke adjusted so that the weight per container is brought back to the desired amount.
It is a primary object of the present invention to provide an improved container-filling machine whereby the piston stroke can be adjusted during movement of the drive mechanism for the piston so that the machine need not be shut down for such purpose.
It is a further object of the invention to provide an improved container-filling machine whereby the piston stroke can be adjusted automatically, during a filling run, and in response to a variation of weight in the containers so as to maintain the desired weight per container -- again without the necessity of having to stop operation of the machine.